Figure 1: (a) Growth of Prorocentrum minimum, strain JA-98-01, in media with full enrichment (square symbols) or with no phosphate enrichment (triangle symbols); means of triplicate flow-cytometer counts SE. (b) Flow-cytometer plot and fluorescence photomicrographs of Prorocentrum minimum cultures sampled after 26 days in nutrient-replete medium. Biplot of relative cell size (FSC, in arbitrary detector units) and red chlorophyll fluorescence (FL3) showing two morphologies of cells within the sample: R1, high-chlorophyll cells, shown in photomicrograph (i) and R2, low-chlorophyll cells that had incorporated fluorescently labeled bacteria, shown as green-fluorescent inclusions in photomicrograph (ii). (c) Histogram plot showing intensity of green fluorescence in cells differentiated by R1 (red line) and R2 (green filled area), indicating relatively low prevalence of bacteriocytic cells in the high-chlorophyll cell population.